Should all pregnant women be offered an elective cesarean delivery to prevent pelvic floor disorders (PFD) such as urinary and fecal incontinence and pelvic organ prolapse? Magnetic resonance imaging (MRI) can provide stunningly clear images of the musculoskeletal system of the pelvic floor, as well as demonstrate evidence of pelvic floor mobility. Recent advances in quantitative electromyography (QEMG) can reveal subtle neuromuscular injury never before available. By combining these two robust diagnostic tools and studying women who are planning a first pregnancy, we plan to focus not only on the outcomes following childbirth, but also to begin to predict who is at increased risk for neuromuscular or connective tissue injury as a result of pregnancy and childbirth. Our central hypothesis for this proposal is that measurements of both the bony pelvis and soft tissue pelvic outlet can predict the likelihood of pelvic floor neuromuscular injury and vaginal delivery. We also hypothesize that pelvic floor neuromuscular injury occurs following vaginal delivery, but is less profound after cesarean delivery. We propose a prospective study in which 200 women entering their first pregnancies are examined by MRI and QEMG before and after pregnancy and again at 6 months postpartum. We propose these specific aims: 1)To test the hypothesis that measurements of the maternal pelvis predict pelvic floor neuromuscular injury after pregnancy and childbirth as measured by QEMG;2) To test the hypothesis that vaginal delivery is associated with greater pelvic floor neuromuscular injury than cesarean deliveries;3) To test the hypothesis that neuromuscular injury detected by QEMG immediately postpartum is responsible for both diminished levator ani function and abnormalities detected by MRI at six months postpartum. The proposed project is significant because we will determine which characteristics can predict neuromuscular injury prior to the onset of labor. We will also determine if pregnancy itself contributes to pelvic floor nerve damage, or if only vaginal delivery is a risk factor. Identifying who is at risk for neuromuscular injury will allow for: 1) better counseling at the time of birth (including decisions about route of birth);2) identification of the injury soon after birth;and 3) appropriate rehabilitation soon after delivery to potentially prevent the onset of symptoms later in life.